A comparative introduction to the biology and limnology of the African Great Lakes

The East African rift valley region contains the earth's largest aggregation of tropical lakes. Three of these lakes- Victoria, Tanganyika, and Malawi-hold one quarter of the earth's total surface freshwater supply, and are home to a myriad of fish species. Apart from the diversity and endemicity of their biota, properties that distinguish the African Great Lakes from their North American counterparts include their great age, long sedimentary records, long residence times, persistent stratification, continuously warm temperatures at all depths, major ion composition, and a propensity for nitrogen limitation. Current management problems include over-fishing, increased input of sediment and nutrients, and in the case of Lake Victoria, loss of endemic fish species and the proliferation of the introduced water hyacinth. As in the Laurentian Great Lakes basin, the harmonization of research programs and management strategies among the various riparian countries is a challenge. While research activities on all three lakes have increased in the last decade, there remains a need for integrated, multi-disciplinary research in order to develop conceptual and numerical models that provide insight into the functioning of large, tropical, freshwater aquatic ecosystems. Particular issues that may be pursued most profitably in the African Great Lakes include the links between climate and biogeochemical cycles, the role of biodiversity in ecosystem functioning, and paleoclimate reconstruction over millions of years.